Fluorinated ether fluids are known in the art to be suitable for use as heat transfer media due to their high chemical and thermal stability, non toxicity and non flammability to be particularly suited for heat transfer applications where such properties, in particular the non flammability, are extremely important for complying with outstanding safety standards. Representative examples of such applications notably include cooling circuits on board of aircrafts, refrigeration systems for supermarkets or heat transfer circuits in industrial plants.
In particular, hydrofluoro(poly)ethers are known in the art to be advantageously used as heat transfer media in low-temperature applications, in particular for transferring heat from a heat source to a heat sink, in view of their low viscosities at low temperatures. However, the main drawback is that hydrofluoro(poly)ether fluids typically require pressurized heat transfer systems to be maintained in a liquid phase over the required operating temperatures.
Among major issues affecting use of fluorinated ether fluids as heat transfer media in heat transfer systems mention can be made of Global Warming caused by emissions of fluids to the atmosphere with particular reference to secondary loop heat transfer systems usually equipped with polymer sealants, suitable for vehicling and circulating the heat transfer fluid from one body to another, which are commonly prone to leakage, in particular in pressurized systems.
Also, as is well known in the art, secondary loop devices are typically affected by moisture, usually vehicled by heat transfer fluids, which condenses and freezes thereon to form frost. This frost greatly decreases the cooling efficiency of the heat transfer system and, if left to accumulate, can even block the flow of the heat transfer fluid circulated through the device to diminish the overall heat transfer capacity of the system.
Thus, EP 0856038 A (MINNESOTA MINING AND MANUFACTURING COMPANY) 5 Aug. 1998 discloses use of hydrofluoroethers as heat transfer fluids for secondary loop refrigeration systems typically operating at temperatures below −15° C.
Also, U.S. Pat. No. 6,148,634 (3M INNOVATIVE PROPERTIES COMPANY) 21 Nov. 2000 discloses use in a multistage refrigeration system of secondary refrigerants notably including perfluoropolyethers commercially available as KRYTOX® K oils and GALDEN® HT fluids.
Moreover, WO 2010/034698 (SOLVAY SOLEXIS S.P.A.) 1 Apr. 2010 discloses use of compositions comprising fluorinated fluids free from functional groups and certain functional (per)fluoropolyether fluids as heat transfer media for transferring heat from a heat source to a heat sink. However, no mention is made therein about compatibility of said heat transfer media towards polymer sealants typically present in secondary loop heat transfer systems.
Further, U.S. Pat. No. 4,955,726 (MONTEDISON S.P.A.) 11 Sep. 1990 discloses use of perfluoropolyethers as heat transfer testing fluids in the electronic industry, in particular for thermal shock test, gross leak test and burn in test applications, at temperatures as low as −65° C. and/or as high as 200° C., depending on the test application. However, these applications require directly contacting the electronic component with the heat transfer fluid by dipping it into the fluid.
There is thus still a need in the art for fluorinated ether heat transfer fluids suitable for use in secondary loop heat transfer systems, said fluids being advantageously endowed with:                viscosities as low as compared with viscosities of hydrofluoro(poly)ether fluids in a wide operating temperature range of from −120° C. up to 180° C.,        boiling points up to 250° C. at atmospheric pressure,        low permeability and high chemical compatibility and resistance towards polymer sealants, in particular at high temperatures,        inherent chemical inertness and stability, and        low solubility of water therein        
to be successfully used in said secondary loop heat transfer systems so as to comply with outstanding safety standards by successfully reducing or even eliminating risks of leaks through polymer sealants and thus corresponding emissions of said fluids to the atmosphere, while increasing efficiency of the systems and minimizing maintenance thereof.